Morphology of rat testis preserved in three different fixatives.

Histopathological examination of testes is important in assessing spermatogenesis and testicular function. Modified Davidson's fluid (mDF) has been proposed as a superior substitute for Bouin's fluid (BF) for fixation of adult animal testes. Besides, 4% paraformaldehyde (PFA) has been commonly used to fix testes with convenience. We compared the morphology of the rat testis fixed in 4% PFA, mDF, or BF using hematoxylin and eosin (HE)-stained sections. Fixation in 4% PFA resulted in obvious tissue shrinkage artifacts, especially between seminiferous epithelium cells. Shrinkage artifacts were also observed in the central area of the testes fixed in BF. Use of mDF did not cause shrinkage artifacts between seminiferous tubules, though a small amount can be observed in seminiferous tubules between germ cells. Clarity of nuclear detail in testes fixed in mDF and BF is better compared to 4% PFA. Our study demonstrated that fixation in mDF provided better morphologic details in the rat testis as compared with 4% PFA and BF.